Half-Marathon Special: Big Time

The half-marathon is the fastest growing distance in our sport. In fact, the number of people who've raced 13.1 miles has nearly doubled in the past decade. Pick a training plan that's right for you—and then join the half-marathon boom yourself.

Many half-marathoners who are gunning for PRs know that they need speedwork to hit their goal, but you can get too much of a good thing—especially if you start too soon. "You need endurance before you build speed and strength," says Joe McConkey, head coach of the Boston Running Center, who urges PR-seekers to do lots of base miles and hill work early in their training to develop aerobic capacity. "Then your cardio system is ready for some quality speed and strength work."

This quality won't come easy. "Most people going into the half run medium hard," says Terrence Mahon, coach at the Mammoth Track Club. "They never run hands-on-their-knees hard. But if you've only trained at the lower end of the spectrum, you haven't trained your muscle fibers to go fast. And you don't want to call on them in the last 10 percent of a race if you've never called on them before."

REAL RUNNER: Rachel ScheinerAge 40

Rachel Scheiner wasn't ready to slow down when she hit 40. The college instructor has run "zillions" of half-marathons, she says, but her running peak came back when she was 33. So she set out to train smarter—and break her PR.

Her plan wasn't exactly easy. She decided to race her big half in May—right as she was training for an Ironman triathlon in June. That meant Scheiner had to build endurance and speed at the same time. She did track workouts once a week and sped up her tempo runs. To develop her base, Scheiner made sure to jog the rest of her miles on the days she did speed workouts. "Running hard and then jogging helps with your endurance," she says. "If you've done that kind of training, there's way less of a chance with a half that you're not going to finish or you're going to cramp up."

Or slow down. Scheiner's 1:31 finish in the Kirkland (Washington) Half-Marathon won the 40-to-49 age division of a crowded women's field. "Honestly, I felt great the whole race, but I got this real high in the last half mile when I realized I was going to break my old record," says Scheiner. "It's nice to know that I can get faster—and smarter—as I get older."